Light control fixture



Feb. 21, 1956 s. H. LEE

LIGHT CONTROL FIXTURE Original Filed Nov. 14, 1949 fan FIG -4 United States Patent LIGHT CONTROL FIXTURE Sherman H. Lee, San Francisco, Calif., assignor of onehalf to Cepco, Inc., San Francisco, Calif., a corporation of California, and one-half to Lippincott & Smith, San Francisco, Calif., a partnership Original application November 14, 1949, Serial No. 126,991. Divided and this application April 18, 1951, Serial No. 221,711

4 Claims. (Cl. 189-84) This application is a division of my copending application Serial No. 126,991 filed November 14, 1949, now Patent No. 2,698,071, and relates to light control units of the louver type, adapted to be mounted below a light source and direct the light downwardly while preventing direct view of the light and glare from any normal point of view. Particularly the invention relates to such units as are intended to cover an entire ceiling.

Among the objects of the invention are to provide a light control system constructed in modular units which can be adapted to cover a ceiling of any area and substantially any shape; to provide a system wherein the modular units can be shipped in knocked-down form and erected at the site at which they are to be used; to provide a system wherein each unit is hinged so that it may be swung out of the way to permit access to the lights at any part of the main ceiling or roof above the fixture, or can, at will, be removed entirely for cleaning or any other purpose; and, ancillary to the above mentioned objects, to provide a form of construction for the modular units of the frame upon which the grids are hung which, when erected, are rigidly dimensioned so that the grids will swing freely, although closely fitted within the frame; and to provide a grid frame which, while extremely light in construction and offering a minimum degree of interception to the infalling light, is itself rigidly dimensioned and resistant to distortion.

Referring to the drawings, Fig. l is a perspective view of a number of modular units embodying my invention as suspended from a roof or ceiling, and illustrating generally the method of support of the system and the lighting fixtures to be controlled by it, and the freedom of hinging of the light control units themselves;

Fig. 2 is an exploded detail view illustrating the construction of the grid frame and the elements entering into the connection between the frame and the louver grid;

Fig. 3 is a plan view of a section of the grid frame, portions of the structure being cut away to show its construction;

Fig. 4 is a fragmentary vertical section through the louver grid and frame, the plane of section being indicated by the lines 4, 4 in Fig. 3;

Fig. 5 is an exploded view showing another method of constructing the frame of the louver grid.

To provide an adequate light control system of the louver type which will cover an entire ceiling a number of mutually incompatible factors must be reconciled. Practically, it is necessary to make the system in modular units of standardized size and shape, since the cost of tailoring to order the fixtures for a complete ceiling would result in prohibitive expense, whereas almost any ceiling can be fitted by properly designed modular units. The units must be of adequate size since otherwise their assembly and maintenance would be a long and expensive procedure, but, on the other hand, they must not be heavy and clumsy to handle since this again would lead to undue maintenance expense. Free access must be offered to the lights themselves to permit them to be serviced, which 7, 2,735,522 Patented Feb. 21, 1956 means that the grids must be readily removable, which again demands lightness of construction, but since they must fit accurately when in place they must be highly resistant to distortion. A maintenance worker caring for a lighting system of this type is always working overhead and frequently upon a ladder; therefore if the louver grid is to be removed entirely he must handle a structure of considerable sizesay on the order of four feet square which is essentially frail in construction and yet is clumsy and heavy, and this presents accident hazards.

My invention obviates the necessity of complete removal, permitting the grids to be swung out of the way to give full access without ever requiring that their entire weight be lifted or that the worker descend a ladder carrying the same. Furthermore, since the grid frames can be made weighing half or less than half of those of the prior art the entire problem is greatly simplified.

Fig. 1 shows the general makeup of a section of a system comprising six modular units in accordance with my invention. A hanger frame comprising side members 1 and transverse members 1 is suspended from a roof or ceiling by means of vertical hanger rods 3 secured at each corner of the hanger frame. Fluorescent or other lamps 5, mounted on fixtures 7, may be mounted directly on the ceiling or may be supported on stretcher bars (not shown) secured to the hanger rods, as circumstances dictate.

The cross members 1' divide the rectangular hanger frame into similar rectangular units, preferably square, and within each of these square units 'is fitted a grid frame and louver assembly 11, each of the grid frames being supported in the hanger frame by two pairs of retractable pins positioned near the ends of opposite sides of the frame which engage holes in the frame members (as will be described later), the pins acting both as latches and hinges, so that when either pair is retracted the section can swing down upon the other pair of hinges as is shown in the figure. Since the grid units are square it is necessary to provide only two pairs of pins, since the units can be rotated within the hanger frames to swing in any direction desired.

The rectangular grid frames are hung within each unit of the hanger frame. The grid frame itself is of a closed or box section. These sections can be formed in a number of ways, one such formation being shown in Figs. 3 and 4. In this method of construction the frame consists of two channels 51 and 52 nested together to form a closed section of the box girder type, the channels being firmly secured as by spot welding the horizontal channel flanges to one another, thereby to form a unitary structure, the channel flanges thus acting as connecting walls for the channel webs or faces. Vertical slots 53 are formed in the inner face or web of the frame at intervals corresponding to the spacing which is to be used for the elements of the louver grid. Communicating with each slot is a hole 55 formed in the upper horizontal flanges of both channels.

The louver grid 57 of mutually intersecting strips joined in the well-known egg crate manner is preferably formed of much thinner material than is customary for this purpose, the material used being not over twenty-five thousands of an inch thick while it may be as thin as five thousandths of an inch. The ends of each strip are rolled as is shown at the reference character 59 and the rolled ends are inserted through the holes 55 so that the strips 57 project out through the slots 53. The distances between the rolled portions 57 at opposite ends of each strip are accurately determined so that the entire grid may easily be slipped into place and there is normally no tension on the frame imposed by the louver strips. Anything which tends to skew or distort the frame will, however, impose tension on the louver strips and supply a restoring force which opposes the skew. The same is true of'anything which tends to bend or otherwise displacethe' louver strips themselves. It is this which" per-' units of the use of a light material for the louvers. Past practice has been to use open side frames with the ends of the louvers merely projecting into a channel-shaped section so that the louvers are support'edonly by their own rigidity. This has necessitated the use of material of approximately 16 B and S gage, which is fifty-one thousandths of an inch thick and, accordingly, if made of the same material as used in louvers constructed in accordance withmy invention weighs anywhere from about two to five'times as much. The weight of the frame which holds the louvers. will not be greatly different in either case, and in any event it forms but a small fraction of the weight of the assembled'grid. The lighter weight of the grids formed in accordance with my invention leads to savingin cost'of original manufacture and in handling and shipping as well as economy of maintenance.

In order to retain the grids in place a cover strip 66 is preferably screwed or otherwise secured over the upper webs of the frames and the holes 55.

Fig. 5 shows a modified form of grid frame which permits of even cheaper and lighter construction. in this case the inner element of the grid frame comprises a channel 61 having an upwardly extending lip 63 from the'lower'fiange 64 of the channel. Slots 53 in the inner Web, communicating with holes 55' in the upper flange, are formed as before, but the box section of the frame is closed by a' simple angle 65, the upper leg of which serves both as a connecting wall for the web portions of the frame and in place of the separate cover plate 60 While the rear leg closes the section. Parts of the frame may be joined by spot welding positioned, for example, as indicated by the dotted circles 67 and 69.

The grid frames are suspended within the hanger frames on retractable hinge pins 71. Pairs of these pins are mounted at each end of opposite sides of the grid frame adjacent the adjoining sides, and engage holes formed in the hanger frames and positioned accurately with relation to the junction between members 1 and 1'. The position ofthe' hinge pins is not of critcal importance. They should be fairly close to the ends of the grid frame sides so as to make the full. area of each modular section available for work above, but they should also be easily reached from below. A convenient position is between the first and second louver considered from either end of the grid frame.

The cleaning of the grid is rendered easy because of the fact that the frame section is entirely closed and there is no open channel section for dust to settle in.

While I have described in detail only the normal or standard square modular unit, it will be apparent tlat as in all types of modular construction fractional units may be provided. in these cases the hanger frame dimensions will normally be either one-half or one-quarter of'whatever size may be adopted as the standard modular unit. Such sections require a certain amount of hand tailoring and will not usually permit the convenience of swinging on either of two 90 axes as does the square unit; It will ordinarily be found more convenient, however, to have oblong rectangular sections turn on axes in their'long dimensions, and swinging in this manner can be'considered a semi standard.

I consider one of the principal advantages of a light control system made in accordance with my invention tobe the fact that the elements can be constructed with a greater degree of accuracy than is customary in sheet metal work of this class. All measurements and fittings can be'accomplished at the factory and al hough the parts are shipped in disassembled form factory accuracy is automatically obtained when they are erected. The hinging of .the grid junits requires that the grid frames fit closely biitfreely withinthe hanger frames, with tolerances held within one-thirty-second of an inch, an accuracy not usually obtainable in sheet metal work. The various features here-described all contributeto' this accuracy andrnake' the system workable.

A fairly Wide choice of matrials is available for construction. The hanger stem assembly will normally be of steel, but the hanger frames may be of either steel or aluminum and so'm'ay the grid frames: For the louvers themselves plastic may be added to the materials mentioned for the frames. l'prefer', however, to use metal louvers, since metal'is fireproof and'not subject to major deformations under unusual conditions of temperature or moisture. Since" the louvers can be formed of thin aluminum or thinner steel, however, the fully assembled frame can be madeas light as it' could be with plastic louvers of ordinary construction and-this possesses the additional advantage that the light intercepted is less than when thicker and heavier construction is used. The effect of the light construction is cumulative, since lighter louvers require lighter grid frames and these, in turn, permit the useof lighter hanger frames. Using the maximum. thickness of metal here suggested the percentageof direct- 1y downwardly projected light intercepted by the louvers" is less than three percent. Angularly directed light will, of course, be intercepted in part by any louver system" and the proportion of this light which is made effective for actual use by reflection depends upon the finish applied to the louvers. With polished steel or aluminum up to ninety-eight per cent of the obliquely directed light may be used, whereas if the louvers 'are finished in dead black, as may be required for some specialized installations, the proportion of obliquely directed light made available may drop'to three or'four per cent. In normal applications the figures will lie somewhere between these extreme values.

Polished metal louvers will give specular reflections from some angles. The most useful finishes are mat surface aluminum and white enamel, both of which give a high degree of utilization of oblique light. Colored enamels may be used for decorative purposes or for color correction. the equipment of my invention, but the invention does permit their utilizationto the fullest extent.

I claim:

1. A light control unit comprising a rectangular grid frame each side whereof comprises'a channel'rnember having a web formingthe inner periphery of said' frame and having spaced slots formed therein perpendicular to the length of said channel and holes'in oneflange of said member adjacent to said web and opening into said sl'ots,.' a grid of rectangularly intersecting louvers the ends whereof extend through opposite sidesof said frame, a roll of a' diameter to permit insertionthroughsaid hole formed in the end of each louver inserted in'said hole and abutting said channel adjacent said slots, anangular member having a flange projecting inwardly and secured over said channel member to" close the same forming a box sectiontherewith and covering said holes to prevent the withdrawalof said louvers from said slots.

2. A- light control unit'compris'ing a frame of box girder section comprising spaced inner and outer webs connected" by connecting walls disposed'normal to said webs and having a plurality of spaced slots extending across the inner web thereof and holes formed'in one of said connecting walls opening into the" slots-in the adjacent web, a grid of intersectinglouvers within said frame, theends of each louver extending'through eor respondingslots on opposite sides of the frame, a roll formed on each end of each louver of a diameter adapted to pass'through said holes in said one connecting wall of said box-girder section, said rolls-restingj-against the inner websof said frame, and' means operatively con-- nected to said one connecting wall and covering the'holes in. said .wall therebyto retain the ends of "said louvers withinisaid slots. h

3. A lightcontrol unit comprising a rectangular frame Such modifications are riot peculiar to of box-girder section including a channel member having a web forming the inner periphery of said frame and an outer member engaging the flanges of said channel member to complete said box section and form the outer periphery of said frame, said channel member having slots extending across the web thereof spaced around the inner periphery of said frame and holes in one flange each communicating with a corresponding slot, a grid of intersecting louvers within said frame, the ends of each louver extending through corresponding slots on opposite sides of said frame, rolls formed on the ends of each louver resting against said web within the section of said frame said rolls being of a diameter to permit insertion through said holes, and a cover means operatively connected to said one flange and overlying said holes thereby to retain the ends of said louvers in position within said slots.

4. A light-control unit in accordance with claim 3 wherein the outer member of said frame is integral with said cover means, forming an angle-section therewith.

References Cited in the file of this patent UNITED STATES PATENTS 660,196 Myers Oct. 23, 1900 877,767 Greilick Jan. 28, 1908 978,466 Mathews Dec. 13, 1910 1,185,642 Emerson June 6, 1916 1,426,736 Hess Aug. 22, 1922 1,540,788 McClure June 9, 1925 1,622,363 Wulftange Mar. 29, 1927 1,641,523 Bell Sept. 6, 1927 1,732,527 Nagin Oct. 22, 1929 1,951,653 Green Mar. 20, 1934 2,396,735 Leigh Mar. 19, 1946 2,464,442 De Roo Mar. 15, 1949 

